N,K = map(int, input().split())

mod = 10**9+7

g1 = [1]*(N+1)
g2 = [1]*(N+1)
for i in range(1, N+1):
    g1[i] = (g1[i-1]*i)%mod
    g2[i] = (g2[i-1]*pow(i, mod-2, mod))%mod

def cmb(n, r, mod):
    if n < r or r < 0:
        return 0
    return (g1[n]*g2[n-r]*g2[r])%mod

ans = 0
if N == K:
    for i in range(1, N):
        ans += i * cmb(N, 2, mod) * g1[N-2] % mod
        ans %= mod
else:
    for i in range(1, N):
        ans += i * (g1[N-1]*g2[N-1-K] + cmb(K, 2, mod)*g1[N-2]*g2[N-K]) % mod
        ans %= mod
    ans += N * g1[N-1] * g2[N-1-K] % mod
    ans %= mod

print(ans)